One prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,065,018, entitled “Synchronizing Recovery Log Having Time Stamp To A Remote Site For Disaster Recovery Of A Primary Database Having Related Hierarchial And Relational Databases”. This prior art method is a method and apparatus to synchronize recovery logs transmitted to a remote site for recovering related databases having different logical structuring. In one embodiment, the related databases are a hierarchial structured database such as IMS and a relational structured database such as DB2.
The present invention differs from the above prior cited art in that the present invention focuses on a REBUILD recovery process as a method that moves an entire auxiliary database forward in time by (1) loading the entire database from a set of dump tapes or from a mirrored snapshot of an existing database, and (2) applying audit trail images to bring the auxiliary database forward in time. The prior art involves a method that is loosely similar to the REBUILD recovery process, but the present invention provides a solution to the shortcomings of loading the entire database from one or more sets of dump tapes which takes inordinate amounts of time.
Yet another prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,377,959, entitled “Redundant Database Recovery Through Concurrent Update And Copy Procedures”. This prior art method is a transaction processing system that continues to process incoming transactions during the failure and recovery of either of two duplicate databases. One of the two duplicate databases is assigned “active” status and the other is maintained with “redundant” status. All incoming queries are sent only to the active database and all incoming updates are sent to both active and redundant databases. When one database fails, the other is immediately reassigned active status if not already active and continues to process incoming queries and updates during the failure. When the failed database is repaired and restarted, all records are flushed therefrom and the failed database is reconstructed using interleaved copy and update operations in a single pass through the active database. Incoming transaction and copy operations are interleaved according to a queue thresholding method for throttling copy operations responsive to increased numbers of incoming transactions. The transaction processing system remains operational both during the failure and during the recovery activities and reaches full recovery without downtime.
The present invention differs from the above prior cited art in that the present invention focuses on methods relating to a specialized form of recovery: a REBUILD recovery. The method of the present invention relates to a backup source that is required for a REBUILD recovery, while an online database recovery process such as that described by the prior art method utilizes no such backup mechanism. The method of the prior art teaches only methods relating to online database recovery.
Yet another prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,247,023, entitled “Method For Providing Database Recovery Across Multiple Nodes”. This prior art method is a three-phase database crash recovery mechanism and detailed including a forward phase, a backward phase, and a third, so-called “sideward” phase for recovery of transactions which were interrupted at the time of the crash, using Global Transaction IDs to track the status of the transactions at the coordinating and at the participating nodes. Depending upon the status of the transaction at the time of the crash, either a query message to the coordinating node or a vote message to the participating nodes is generated and processed, thereby allowing most interrupted transactions to be completed. Additional implementations are provided for crash recovery, without duplication of efforts, across multiple nodes in a parallel database environment, for cascaded transactions wherein the database recovery at a local node is triggered by database recovery at a remote node in the parallel system, and for concurrent recovery, wherein database recovery is started concurrently at both transaction coordinator and participant nodes.
The present invention differs from the above prior cited art in that the prior art invention focuses on a “database crash recovery mechanism” that is similar to the recovery mechanism described in U.S. Pat. No. 6,377,959 in that it teaches methods relating to online database recovery. The method of the present invention, however, relates to a backup source that is required for a REBUILD recovery, while an online database recovery process such as that described by the prior art method, utilizes no such backup mechanism.